As the volume of data stored on personal computers becomes more and more important, external mobile storage devices, having portable and large capacity storage features, are provided to serve as auxiliary storage means. Such conventional storage devices are generally referred to as external hard disks, media disks, or media centers, and are connectable to personal computers for data transfer between the personal computer and the external storage device. They are usually used to store personal data such as pictures, audio and video files.
As is well known, these storage devices can be directly attached to a display device or a player so as to readily display or play the data stored in the storage device, for example when the data are of video, audio or picture type.
The existing storage devices allow mobility/portability of the content, so that the content is no longer only bound to the specific personal computer to which it was originally downloaded or received in another way.
However, the data stored are more vulnerable in the storage device than when they are stored in the personal computer. Indeed, the existing storage devices are generally deprived of content protection. Their small size further exposes them to risks of robbery. Accordingly, the content of the storage devices might be fraudulently copied or erased.
In the same time, the data stored in the storage devices tend to become more and more personal. Therefore, another concern with such storage devices is to ensure that only authorized users may access the data stored, and in particular that the access authorization be provided by the master user to which the storage device belongs.
There exist systems and methods widely implemented to protect content stored on external storage devices. These existing systems lie on complex processing of data and/or on complex identification infrastructure, such as password-based or biometrics identification infrastructures, or on external authorization entities, such as a commercial server using a trusted party. Such approaches involve important costs and complex interactions with the users. They are also reliant on user remembering passwords or identification information.
There exist other systems and methods called CPRM (Content Protection for Recordable media) and AACS (Advanced Access Content System) that control copying, moving, and deletion of digital media on a host device, such as a personal computer, or other digital player. These systems rely on key management for interchangeable media, content encryption, and media-based renewability. They involve a number of entities interacting in a commercial infrastructure for ensuring protection of content and providing access authorizations to other users (content owner, clearing house, content reseller, client). These systems are quite complex and provide a non-personal solution.